L14 Kin Selection 2 Flashcards
Frequency dependent selection
Less offspring => more fitness
More offspring => less fitness
even sex ratio => males and females have equal average fitness
The two castes
- Queens
2. Workers
Darwin on social insects
Is kin selection the answer?
Ants, bees and wasps are haplodiploid
Males are haploid
Females are diploid
Full sisters and super sisters
r = 0.75
Males are always half brothers to their siblings
r = 0.25
Workers reproduction
- workers are unmated in most species but can produce sons asexually
- related to their own kids by 0.5
But! Haplodiploids also have lower sister-brother relatedness
also, eusociality arose in several diploid taxa and there are some non-eusocial haplodiploids too
maybe haplodiploidy is a red herring
Why was this rather obvious theory (monogamy) ignored until the 2000s?
Honey bees are not monogamous
However, the ancestors of all eusocial insects were probably monogamous
Cooperative breeding
Cooperative breeding
- Evolve from relatively monogamous ancestors - Worth helping your parents to rear siblings if they are your full siblings and not half siblings
So, what about haplodiploidy?
- seems monogamy is more important
- the fact that eusociality evolved so many times in haploidiploids mean something?
Virgin haploidiploids can and do reproduce
Haplodiploid
- Females can have kids without a mate
- Can only produce sons
- Some of the nests are full of boys
- Other nets have a mixture of males and females since the queen has successfully mated
Virgin reproduction selects for “split sex ratios”
So the earliest workers might have mostly reared full sisters (r=0.75) which are more valuable than their own offspring (r=0.5)
Relatedness-dependent matricide in wasps
Matricide
- Whether or not the mother is killed is correlated to how often the mother has remated
- Wasps can tell how many times the mother has mated
- If she’s singly mated, they kill her
Relatedness-dependent matricide in wasps
Matricide
- Whether or not the mother is killed is correlated to how often the mother has remated
- Wasps can tell how many times the mother has mated
- If she’s singly mated, they kill her
Worker policing
- if worker most related to the sons of the queen, workers don’t really reproduce in this case
- if workers most related to the sons of other works, workers reproduce more in this case
Worker policing
- if worker most related to the sons of the queen, workers don’t really reproduce in this case
- if workers most related to the sons of other works, workers reproduce more in this case
- when policing is effective, workers don’t bother trying to lay eggs
Dominant meerkats kill subordinates’ offspring and evict the transgressor
Subordinates to try to breed, kill the offspring and kick out that meerkat
Adult phenotype is determined by juvenile environment, which individuals have little control over
Whether you develop into a queen bee or worker bee
- Queen bees grow up in a queen cell
- Workers have little option but to cooperate
The monogamy hypothesis
Monogamy - genetic monogamy
- The whole colony has the genes from one mum and one dad - Just as related to your own kids than you are to your siblings - If rearing siblings than having your own kids, then you become a sterile helper - The VERY first bee is well adapted to be a solidary organism, doesn't have social behaviours just yet so B is unlikely to be a lot higher than C
eusociality
Eusocial animals share the following four characteristics: adults live in groups, cooperative care of juveniles (individuals care for brood that is not their own), reproductive division of labor (not all individuals get to reproduce), and overlap of generations (Wilson 1971).
